The "Jon" indeed is very interesting....
"JOHANN" or "JOHANNES" is always shortened to "JOH" (or, as in this case, only with "J")what may be read as "JON" in engraved letters.. This is to be seen in a russian forum:
http://forum.guns.ru/forum_light_message/112/397952.html

I cannot imagine that any European maker would write "JON".... I think the sign is added later...

Cheers,
Gunwolf

Last edited by Gunwolf; 09/25/16 06:50 AM.